The present invention relates generally to the field of data storage systems, and more particularly to compensating for the loss of current through shorted tunneling magnetoresistance (TMR) sensors.
TMR sensors can be used to read magnetic data from a magnetic tape media. The thickness of the tunnel junction (TJ) is very small, of the order of 1 nm. Electrical shorts across these thin TJs can result in current bypassing the bulk area of the TJ and going through the short. Shorts can occur from various sources, such as dielectric breakdown or by scratches which occur during manufacturing (lapping) or in a tape drive by asperities on the tape which can cause scratches.
TJs can be damaged by dielectric breakdown, and the mean dielectric breakdown time for a group of self-similar TMRs subjected to a voltage stress decreases with increasing voltage. The process of running tape across a TMR sensor can also result in a short across the TJ. In this case, often the short diverts current away from the active portion of the TMR, and at a fixed current, results in a drop in amplitude.